Falcone, one of the 50 MTA K-9 units, reacts after finding an explosives odor used during a training exercise in a train car at Grand Central Terminal in Manhattan. (March 1, 2013)

(Credit: Rory Glaeseman)

Falcone, one of the 50 MTA K-9 dogs, receives a reward toy after finding a sample during a training exercise with his partner, Sgt. Edward O'Flaherty, at Grand Central Terminal in Manhattan. (March 1, 2013)

(Credit: Rory Glaeseman)

Falcone, one of the 50 MTA K-9 dogs, sits waiting for a training exercise at Grand Central Terminal in Manhattan. (March 1, 2013)

Falcone, one of the 50 MTA K-9 dogs, sniffs out an odor of explosives with his partner, Sgt. Edward O'Flaherty, during a training exercise in a train car at Grand Central Terminal in Manhattan. Falcone is named for Detective John M. Falcone, of the City of Poughkeepsie Police Department, who was shot and killed in February 2011. (March 1, 2013)

(Credit: Rory Glaeseman)

Lt. John Kerwick, left, of the MTA K-9 unit, and Sgt. Edward O'Flaherty prepare a training exercise with one of their dogs at Grand Central Terminal in Manhattan. (March 1, 2013)

(Credit: Rory Glaeseman)

Falcone, one of the 50 MTA K-9 dogs, participates in a training exercise with his partner, Sgt. Edward O'Flaherty, at Grand Central Terminal in Manhattan. (March 1, 2013)

(Credit: Rory Glaeseman)

Falcone, one of the 50 MTA K-9 dogs, participates in a training exercise with his partner, Sgt. Edward O'Flaherty, at Grand Central Terminal in Manhattan. (March 1, 2013)

(Credit: Rory Glaeseman)

Falcone, one of the 50 MTA K-9 dogs, participates in a training exercise with his partner, Sgt. Edward O'Flaherty, at Grand Central Terminal in Manhattan. (March 1, 2013)

Lt. John Kerwick, tactical commander of the MTA K-9 unit, talks about the history of the unit at Grand Central Terminal in Manhattan. (March 1, 2013)

(Credit: Rory Glaeseman)

Falcone, an MTA K-9 dog, sniffs out a sample of an explosive during a training exercise in a train car at Grand Central Terminal in Manhattan. (March 1, 2013)

(Credit: Rory Glaeseman)

Falcone, left, plays with his partner, Sgt. Edward Flaherty, after he successfully found an odor sample of explosives during a training exercise at Grand Central Terminal in Manhattan. The dogs are rewarded with a moment of play if they find the sample during a training session. (March 1, 2013)

(Credit: Rory Glaeseman)

Falcone, one of the 50 MTA K-9 dogs, finds an explosives odor sample during a training exercise at Grand Central Terminal in Manhattan. (March 1, 2013)